The objective of the proposed project is to analyze the data from an observational home-based study of infant-environment interaction using a newly developed technique which is designed to provide a complete and detailed description of contingencies between the infant and his world. The project will complement a set of laboratory experiments designed to improve our understanding of how infants come to perceive their control of external events. The analytic technique is based on a model of contingency clarity, and represents a significant advance over current methods of interaction analysis in that a) it is event-based, rather than time-based, examining flexible units of time for the occurrence of contingent stimuli; and b) it considers both the proportion of responses which are followed by contingent stimuli (the sufficiency of the response in producing the stimulus), and the proportion of stimuli which are preceded by a response (necessity of the response for occurrence of the stimulus). This represents a more sophisticated definition of contingency than has heretofore been proposed and is hypothesized to be more closely analogous to the way in which individuals gauge the level of contingency between their own behavior and stimulus events.